川村 和也

Needle insertion treatments require accurate placement of the needle tip into the target cancer. However, it is difficult to insert the needle into the cancer because of cancer displacement due to the organ deformation. Then, a path planning using numerical simulation to analyze the deformation of the organ is important for the accurate needle insertion. The objective of our work is to develop and validate a viscoelastic and nonlinear physical liver model. First, an overview is given of the development of the physical liver model. Second, the experimental method to validate the model is explained. In-vitro experiments that made use of a pig's liver were conducted for comparison with the simulation using the model. Results of the in-vitro experiment showed that the liver model reproduces 1) the relationship between needle displacement and force during needle insertion, 2) velocity dependence of needle displacement and force when a puncture occurs, and 3) nonlinear and viscoelastic response of displacement at an internally located point displacement, with high accuracy.

The purpose of this study is to develop a surgical robot system with heartbeat canceller for endoscopic off-pump coronary artery bypass. The system is composed of the following two items. (i) heartbeat canceller (ii) master-slave surgical robot. In this paper, regarding (ii), we report the features of surgical robot and some experiments using it. The experiments are (a) insert a surgical needle into tissue (thymus) as in vivo experiment using a hog, (b) ligation of a rayon thread. As a result, we confirmed that the surgical robot accomplished two procedures.

Medical technology has advanced with the introduction of robot technology, making previous medical treatments that were very difficult far more possible. However, operation of a surgical robot demands substantial training and continual practice on the part of the surgeon because it requires difficult techniques that are different from those of traditional surgical procedures. We focused on a simulation technology based on the physical characteristics of organs. In this research, we proposed the development of surgical simulation, based on a physical model, for intra-operative navigation by a surgeon. In this paper, we describe the design of our system, in particular our organ deformation calculator. The proposed simulation system consists of an organ deformation calculator and virtual slave manipulators. We obtained adequate experimental results of a target node at a nearby point of interaction, because this point ensures better accuracy for our simulation model. The next research step would be to focus on a surgical environment in which internal organ models would be integrated into a slave simulation system.

This paper shows the viscoelastic and nonlinear organ deformation model for organ model-based control of needle insertion, in which the deformation of an organ is calculated intraoperatively and the needle is manipulated with organ deformation taken into consideration. An organ model including such detailed material characteristics is important to achieve the control method in question. Firstly, the material properties of the liver are modeled from the measured data and its viscoelastic characteristics are represented by differential equations, including the term of the fractional derivative. Nonlinearity in terms of the fractional derivative was measured, and modeled using the quadratic function of strain. Next, a solution of an FE model using such material properties is shown. We use sampling time scaling property as the solution for the viscoelastic system. The solution for a nonlinear system using the Modified Newton-Raphson method is also shown. Finally, the organ deformation, assuming the needle is inserted, is simulated using an organ model and the overall deformation and distribution of the strain at each element is computed in these simulations.

this paper shows the viscoelastic and nonlinear organ deformation model for organ model-based control of needle insertion, in which the deformation of an organ is calculated intraoperatively and the needle is manipulated with organ deformation taken into consideration. An organ model including such detailed material characteristics is important to achieve the control method in question. Firstly, the material properties of the liver are modeled from the measured data and its viscoelastic characteristics are represented by differential equations, including the term of the fractional derivative. Nonlinearity in terms of the fractional derivative was measured, and modeled using the quadratic function of strain. Next, a solution of an FE model using such material properties is shown. We use sampling time scaling property as the solution for the viscoelastic system. The solution for a nonlinear system using the Modified Newton-Raphson method is also shown. Finally, the organ deformation, assuming the needle is inserted, is simulated using an organ model and the overall deformation and distribution of the strain at each element is computed in these simulations. © 2007 IEEE.

It is generally difficult to determine the material values of human tissue to input into an organ deformation model, because the material properties of human tissues are inherently uncertain because of their individual differences. In our work, we developed a promising approach that allows identification of the material parameters of the organ model by using information obtained during surgery. The effectiveness of the method was shown through both numerical and physical experiments. As a result of both experiments, it was shown that the material parameters of the organ model were accurately identified. © 2007 IEEE.

Medical technology has advanced with the introduction of robot technology, making previous medical treatments that were very difficult far more possible. However, operation of a surgical robot demands substantial training and continual practice on the part of the surgeon because it requires difficult techniques that are different from those of traditional surgical procedures. We focused on a simulation technology based on the physical characteristics of organs. In this research, we proposed the development of surgical simulation, based on a physical model, for intra-operative navigation by a surgeon. In this paper, we describe the design of our system, in particular our organ deformation calculator. The proposed simulation system consists of an organ deformation calculator and virtual slave manipulators. We obtained adequate experimental results of a target node at a nearby point of interaction, because this point ensures better accuracy for our simulation model. The next research step would be to focus on a surgical environment in which internal organ models would be integrated into a slave simulation system.

this paper shows the viscoelastic and nonlinear organ deformation model for organ model-based control of needle insertion, in which the deformation of an organ is calculated intraoperatively and the needle is manipulated with organ deformation taken into consideration. An organ model including such detailed material characteristics is important to achieve the control method in question. Firstly, the material properties of the liver are modeled from the measured data and its viscoelastic characteristics are represented by differential equations, including the term of the fractional derivative. Nonlinearity in terms of the fractional derivative was measured, and modeled using the quadratic function of strain. Next, a solution of an FE model using such material properties is shown. We use sampling time scaling property as the solution for the viscoelastic system. The solution for a nonlinear system using the Modified Newton-Raphson method is also shown. Finally, the organ deformation, assuming the needle is inserted, is simulated using an organ model and the overall deformation and distribution of the strain at each element is computed in these simulations.

It is generally difficult to determine the material values of human tissue to input into an organ deformation model, because the material properties of human tissues are inherently uncertain because of their individual differences. In our work, we developed a promising approach that allows identification of the material parameters of the organ model by using information obtained during surgery. The effectiveness of the method was shown through both numerical and physical experiments. As a result of both experiments, it was shown that the material parameters of the organ model were accurately identified.

This paper shows the viscoelastic and nonlinear organ deformation model for organ model-based control of needle insertion, in which the deformation of an organ is calculated intraoperatively and the needle is manipulated with organ deformation taken into consideration. An organ model including such detailed material characteristics is important to achieve the control method in question. Firstly, the material properties of the liver are modeled from the measured data and its viscoelastic characteristics are represented by differential equations, including the term of the fractional derivative. Nonlinearity in terms of the fractional derivative was measured, and modeled using the quadratic function of strain. Next, a solution of an FE model using such material properties is shown. We use sampling time scaling property as the solution for the viscoelastic system. The solution for a nonlinear system using the Modified Newton-Raphson method is also shown. Finally, the organ deformation, assuming the needle is inserted, is simulated using an organ model and the overall deformation and distribution of the strain is computed in these simulations.

Organs have many vulnerable tissues such as blood vessels and nerves which must never be damaged. This paper shows a control method which prevents the overload of vulnerable tissues. Firstly, the force control method, which prevents overload, is shown. Secondly, a FEM-based stress obsever using the organ model is described. Finally, a control method incorporating the first and second steps, and which prevents overload at vulnerable tissue, is shown. Based on the experimental result of positional and stress data; it is shown that the stress at vulnerable tissues didn't widely exceed limit stress, in the event that a target position potentially resulting in damage to vulnerable tissue was ordered.

Minimally invasive surgery that is less safe for human beings cannot spread. We propose a system that avoids damaging the nerves and blood in the surgical approach to safe minimally invasive surgery. The system consists of a model of the operative part and a surgical manipulator. The model shows the pressure on the nerves and bloods in surgical procedure. The model requires precise measurement of the physical properties of soft tissue in the view of the surgical procedure. We propose new and precise model for muscle's heterogeneity properties. In this paper a viscoelasticity test is examined to some muscle samples involved in a rectus femoris muscle. Approximating each result of heterogeneity properties to the three-elements model quantitatively showed the difference in the physical properties of each part. This precise three-elements model is build in a simulation of muscle behavior. Comparison of the indentation examinations between real muscle and the simulation confirmed the effectiveness of the parameters obtained from the viscoelasticity examination. The difference between the maximum forces of the indented simulated heterogeneity and homogeneity models is about 21 %. The indented simulation resulted in a need for a heterogeneity model of muscle. In the near future proposed model will be based on the control of a surgical manipulator. Proposed system will provide safe minimally invasive surgery.

Medical robotics have started using methods of minimally invasive surgery as standard, and this technology has been used for remote operations i.e. tele-surgery. There is an actual case which exclusive communication lines were used during robotic tele-surgery. However, using special communication lines is not average method. So, the construction of the general robotic tele-surgical environments is required. In this paper, the simulation system is composed of three modules that have been developed to simulate signal characteristics in a public line. The modules are (1) QoS simulator algorithm, (2) QoS compensation algorithm and (3) Slave simulator algorithm. The requirement of the network QoS to establish the most suitable means of control was clarified. And then, an ultrasonic motor was driven and its performance was experimented to demonstrate the feasibility of (2) QoS compensation algorithm. The output value was compared with the input value of the ultrasonic motor. Buffering the network disorders was shown.